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Old 23rd January 2014, 07:00 PM   #11
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So is it not feasible just to maintain the Pensil R70 baffle dimension with single driver and just add another single driver below the top driver?
No. Not while maintaining the same alignment.
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Old 26th January 2014, 08:17 AM   #12
JoeyGS is offline JoeyGS  Philippines
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Chris and Scott ..... thank for your inputs
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Old 28th January 2014, 10:46 PM   #13
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I'll echo chrisb's recommendation; the microTowers (Castle Howard configuration) are excellent!
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Old 30th January 2014, 05:17 AM   #14
JoeyGS is offline JoeyGS  Philippines
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Thanks cogitech.... will do that in my next build.
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Old 30th January 2014, 05:29 AM   #15
JoeyGS is offline JoeyGS  Philippines
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Default Bracing, Stuffing and Damping .....

As I move forward with a Pensil box design for the CHR-70.3 drivers, several things I need to be clear about bracing, stuffing and damping. When I back read the threads at the fullrange section I get confused as queries and responses are quite floating into bits and pieces......

1. Bracing - I understand that this would prevent resonance of the box walls. Without bracing on the the pensil boxes, is damping the alternative method? I understand damping to be absorbent materials that would prevent the box walls from resonating, am i correct?
2. Damping - What are the recommended damping materials for the Pensil boxes? Where will the damping materials be placed for the pensil box internal walls?
3. Stuffing - I understand that stuffing is used to fill the boxes to prevent standing waves, correct? Polyfills are examples of this as I understand. As stuffing is provided to tune the boxes, where should stuffing be placed? Entire box volume? Or what's the minimum requirement?
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Old 30th January 2014, 01:22 PM   #16
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Re the questions:

1/ Bracing does not prevent resonance. It strengthens the box structure & moves the panel resonant modes to a higher frequency, where they are less likely to be excited. Panel damping (different sort of damping) can reduce the amplitude of panel resonance but unless you know exactly what you are doing, I wouldn't advise it with the pensil cabinets since it typically needs a different type of cabinet construction which was not assumed in the plans.

2/ Stated in the plans; Dacron hollow-fibre pillow stuffing material. The cabinets are not designed / assumed to be lined.

3/ Throughout & adjust density from the default quantity (also listed in the plans) to suit particular requirements / taste. That's why a removable back is specified / recommended
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Old 31st January 2014, 01:41 AM   #17
JoeyGS is offline JoeyGS  Philippines
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Great info Scott. Thanks.

Follow-up questions:

1. There were mention of providing damping materials behind the drivers so that reflections from the walls are prevented to affect the normal movement of the drivers. Are these apart from the specified stuffing material? If so, what type is recommended?

2. Whats the recommended optimum speaker wire gage for the mark audio drivers?

Thanks
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Old 31st January 2014, 02:23 AM   #18
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1/ No. You can if you wish, but it's not a reqirement. If it was, it would be in the plans.

2/ There isn't one. Varies depending on system & personal choice. In general though, assuming you're not wanting to use the wire's LCR properties to shape the response, you want to be using something that keeps voltage drop to a minimum for the given length. That's not a major issue for internal wire; something like 20ga should do for that. It may for normal external runs from amplifer - speaker too for that matter, although slightly heavier is usually a good idea. Up to about 10ft runs, ~14ga should be fine. Some prefer much thinner wire, although resistance can get somewhat high there. A high output impedance amp i(e.g. a typical SET) is lusually less affected by this however. YMMV as always.
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Old 31st January 2014, 02:45 AM   #19
JoeyGS is offline JoeyGS  Philippines
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Maraming Salamat (Thank you very much - in Filipino language)

Kung hei fat choi!
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Old 31st January 2014, 02:51 AM   #20
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Quote:
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2. Whats the recommended optimum speaker wire gage for the mark audio drivers?
We happily ise 2 strands pulled from solid core CAT5.

dave
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